text: Pesticide use raises a number of environmental concerns. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, including non-target species, air, water and soil. Pesticide drift occurs when pesticides suspended in the air as particles are carried by wind to other areas, potentially contaminating them. Pesticides are one of the causes of water pollution, and some pesticides were persistent organic pollutants (now banned), which contribute to soil and flower (pollen, nectar) contamination. Furthermore, pesticide use can adversely impact neighboring agricultural activity, as pests themselves drift to and harm nearby crops that have no pesticide used on them.
  In addition, pesticide use reduces biodiversity, contributes to pollinator decline, destroys habitat (especially for birds), and threatens endangered species. Pests can develop a resistance to the pesticide (pesticide resistance), necessitating a new pesticide. Alternatively a greater dose of the pesticide can be used to counteract the resistance, although this will cause a worsening of the ambient pollution problem.
  The Stockholm Convention on Persistent Organic Pollutants, banned all persistent pesticides,  in particular DDT and other organochlorine pesticides, which were stable and lipophilic, and thus able to bioaccumulate in the body and the food chain. and which spread throughout the planet.  Persistent pesticides are no longer used for agriculture, and will not be approved by the authorities. Because the half life in soil is long (for DDT 2–15 years) residues can still be detected in humans at levels 5 to 10 times lower than found in the 1970s.
  Pesticides now have to be degradable in the environment. Such degradation of pesticides is due to both innate chemical properties of the compounds and environmental processes or conditions. For example, the presence of halogens within a chemical structure often slows down degradation in an aerobic environment. Adsorption to soil may retard pesticide movement, but also may reduce bioavailability to microbial degraders.
  Pesticide contamination in the environment can be monitored through bioindicators such as bee pollinators.